Question

Run the code in Linux and provide the screenshot of the output and input

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>

static void cleanup();
static void docleanup(int signum);

static const char *SERVER_ADDR = "127.0.0.1";
static const int SERVER_PORT = 61234;

static int cfd = -1;

int main(int argc, char *argv[]) {
struct sockaddr_in saddr;
char buf[128];
int bufsize = 128,
bytesread;
struct sigaction sigact;

printf("client starts running ...\n");

atexit(cleanup);
sigact.sa_handler = docleanup;
sigaction(SIGINT, &sigact, NULL);

cfd = socket(AF_INET, SOCK_STREAM, 0);
if (-1 == cfd) {
perror("socket");
exit(EXIT_FAILURE);
}

saddr.sin_family = AF_INET;
saddr.sin_port = htons(SERVER_PORT);
if (0 == inet_pton(AF_INET, SERVER_ADDR, &saddr.sin_addr)) {
fprintf(stderr, "cannot convert %s to IP address\n", SERVER_ADDR);
exit(EXIT_FAILURE);
}
if (-1 == connect(cfd, (struct sockaddr *)&saddr, sizeof(saddr))) {
perror("connect");
exit(EXIT_FAILURE);
}

while (1) {
printf("Enter message: ");

if (NULL == fgets(buf, bufsize-1, stdin)) {
fprintf(stderr, "failed to read stdin\n");
exit(EXIT_FAILURE);
}
buf[strcspn(buf, "\r\n")] = '\0';
printf("user entered: %s\n", buf);

if (-1 == send(cfd, buf, bufsize-1, MSG_NOSIGNAL)) {
perror("send");
exit(EXIT_FAILURE);
}
printf("client sent: %s\n", buf);

bytesread = recv(cfd, buf, bufsize, 0);
if (-1 == bytesread) {
perror("recv");
exit(EXIT_FAILURE);
}
buf[bytesread] = '\0';
printf("client received: %s\n", buf);
if (strncasecmp(buf, "Bye!", 4) == 0) {
printf("server echoed 'Bye!', and exiting ...\n");
break;
}
}

return 0;
}

static void cleanup() {
if (cfd >= 0) close(cfd);
printf("client cleaned up and exiting ...\n");
}

static void docleanup(int signum) {
if (SIGINT == signum) printf("User pressed CTRL-C\n");
exit(signum);
}

Answer 1

The provided code is executed in linux environment.

Screenshots:

Error Statement: The provided code is a client to interact with a socket server. But the provided code is only client code. So it is not possible to connect the server. The client outputs connection is refused and started cleaning up the connection.

Requirements: Server program should be provided to run the server and to interact with it using client program provided.